Make Rust E2E CI fail fast

Add a per-test E2E timeout and run Rust CI tests serially with uncaptured output so stuck replay-backed tests expose the active test instead of hanging silently.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: stephentoub

.github/workflows/rust-sdk-tests.yml

@@ -94,10 +94,11 @@ jobs:
         run: pwsh.exe -Command "Write-Host 'PowerShell ready'"
 
       - name: cargo test
+        timeout-minutes: 90
         env:
           COPILOT_HMAC_KEY: ${{ secrets.COPILOT_DEVELOPER_CLI_INTEGRATION_HMAC_KEY }}
           COPILOT_CLI_PATH: ${{ steps.setup-copilot.outputs.cli-path }}
-        run: cargo test --features test-support
+        run: cargo test --features test-support -- --test-threads=1 --nocapture
 
   # Validates the `embedded-cli` build path on all three supported
   # platforms. This is the only place `build.rs` actually runs (the

rust/tests/e2e/support.rs

@@ -32,10 +32,18 @@ where
     let mut ctx = E2eContext::new(category, snapshot_name)
         .await
         .unwrap_or_else(|err| panic!("create E2E context: {err}"));
-    test(&mut ctx).await;
-    ctx.cleanup(false)
+
+    let timed_out = tokio::time::timeout(default_test_timeout(), test(&mut ctx))
+        .await
+        .is_err();
+    ctx.cleanup(timed_out)
         .await
         .unwrap_or_else(|err| panic!("clean up E2E context: {err}"));
+    assert!(
+        !timed_out,
+        "timed out after {:?} running E2E test {category}/{snapshot_name}",
+        default_test_timeout()
+    );
 }
 
 pub struct E2eContext {
@@ -436,6 +444,14 @@ fn default_event_timeout() -> Duration {
     }
 }
 
+fn default_test_timeout() -> Duration {
+    if cfg!(windows) {
+        Duration::from_secs(300)
+    } else {
+        Duration::from_secs(180)
+    }
+}
+
 pub fn get_system_message(exchange: &serde_json::Value) -> String {
     exchange
         .get("request")